ML24247A164
| ML24247A164 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 09/30/2024 |
| From: | Jeffrey Whited Plant Licensing Branch III |
| To: | Rhoades D Constellation Energy Generation, Constellation Nuclear |
| Kuntz R | |
| References | |
| EPID L-2024-LLR-0018 | |
| Download: ML24247A164 (1) | |
Text
September 30, 2024 David P. Rhoades Senior Vice President Constellation Energy Generation, LLC President and Chief Nuclear Officer Constellation Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - ALTERNATIVE REQUEST RP-01 (EPID L-2024-LLR-0018)
Dear David Rhoades:
By letter dated February 29, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24060A191), Constellation Energy Generation, LLC (Constellation, the licensee) submitted alternative request RP-01 to the U. S. Nuclear Regulatory Commission (NRC) proposing to use an alternative to specific inservice testing (IST) requirements in the 2017 Edition of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code) for certain pumps at Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2, during the sixth IST program interval.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(2), the licensee proposed to implement request RP-01 on the basis that complying with the requirements of the ASME OM Code as incorporated by reference in 10 CFR 50.55a would result in hardship without a compensating increase in the level of quality and safety The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation (SE), that the proposed alternative in request RP-01 will provide reasonable assurance that the core spray system pumps listed in Table 1 of the enclosed SE are operationally ready to perform their safety functions. The NRC staff determined that the licensee has justified that compliance with the testing requirements in the ASME OM Code (2017 Edition) for the pumps listed in Table 1 would result in hardship without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(a)(z)(2).
Therefore, the NRC staff authorizes the proposed alternative in request RP-01 for the sixth IST program interval at QCNPS, Units 1 and 2, which began on August 18, 2023, and is scheduled to end on July 17, 2033.
All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief or an alternative was not specifically requested, and granted or authorized (as appropriate), remain applicable.
If you have any questions, please contact me at 301-415-3733 or via e-mail at Robert.Kuntz@nrc.gov.
Sincerely, Jeffrey A. Whited, Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-254 and 50-265
Enclosure:
Safety Evaluation cc: Listserv Jeffrey A.
Whited Digitally signed by Jeffrey A. Whited Date: 2024.09.30 13:34:09 -04'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST RP-01 SIXTH INSERVICE TESTING PROGRAM INTERVAL CONSTELLATION ENERGY GENERATION, LLC QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 DOCKET NOS. 50-254 AND 265 EPID L-2024-LLR-0018
1.0 INTRODUCTION
By letter dated February 29, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24060A191), Constellation Energy Generation, LLC (Constellation, the licensee) submitted request RP-01 to the U.S. Nuclear Regulatory Commission (NRC) proposing to use an alternative to specific inservice testing (IST) requirements in the 2017 Edition of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code) for certain pumps at Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2, during the sixth IST program interval.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(2), the licensee proposed to implement request RP-01 on the basis that complying with the requirements of the ASME OM Code as incorporated by reference in 10 CFR 50.55a would result in hardship without a compensating increase in the level of quality and safety
2.0 REGULATORY EVALUATION
The NRC regulations in 10 CFR 50.55a(f)(4), Inservice testing standards requirement for operating plants, state, in part, that throughout the service life of a boiling or pressurized-water-cooled nuclear power facility, pumps and valves that are within the scope of the ASME OM Code must meet the IST requirements (except design and access provisions) set forth in the ASME OM Code and addenda that become effective subsequent to editions and addenda specified in 10 CFR 50.55a(f)(2) and (3) and that are incorporated by reference in 10 CFR 50.55a(a)(1)(iv), to the extent practical within the limitations of design, geometry, and materials of construction of the components.
The NRC regulations in 10 CFR 50.55a(z), Alternatives to codes and standards requirements, state that alternatives to the requirements of 10 CFR 50.55a(b) through (h) or portions thereof may be used when authorized by the Director, Office of Nuclear Reactor Regulation. A proposed alternative must be submitted and authorized prior to implementation.
The applicant or licensee must demonstrate that:
(1) Acceptable level of quality and safety. The proposed alternative would provide an acceptable level of quality and safety; or (2) Hardship without a compensating increase in quality and safety. Compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.0 TECHNICAL EVALUATION
3.1 Licensee Request RP-01 Applicable OM Code Edition The licensees IST Code of Record is the 2017 Edition of the ASME OM Code, as incorporated by reference in 10 CFR 50.55a, for the sixth IST program interval at QCNPS, Units 1 and 2, which began on August 18, 2023, and is scheduled to end on July 17, 2033.
ASME Code Components Affected In its submittal, the licensee requests alternative IST requirements for the following four pumps at QCNPS, Units 1 and 2:
Table 1 Component ID Component Description Code Class Pump Group 1-1401A U1A Core Spray Pump 2
B 1-1401B U1B Core Spray Pump 2
B 2-1401A U2A Core Spray Pump 2
B 2-1401B U2B Core Spray Pump 2
B Applicable Code Requirements The IST requirements of the ASME OM Code as incorporated by reference in 10 CFR 50.55a related to this request are as follows:
ASME OM Code, Subsection ISTB, Inservice Testing of Pumps in Water-Cooled Reactor Nuclear Power Plants - Pre-2000 Plants, paragraph ISTB-1400, Owners Responsibility, in subparagraph (d), states that the Owners responsibility includes:
establishing a pump periodic verification test program in accordance with Division 1, Mandatory Appendix V.
Division 1, Mandatory Appendix V, Pump Periodic Verification Test [PPVT] Program, in paragraph V-1000, Purpose, states in part:
the Owner shall establish a pump periodic verification test program for certain applicable pumps that are tested in accordance with para. ISTA-1100 Paragraph V-2000, Definitions, states:
pump periodic verification test: a test that verifies a pump can meet the required (differential or discharge) pressure as applicable, at its highest design basis accident flow rate.
Paragraph V-3000, General Requirements, states in subparagraph (b) that the Owner shall:
perform the pump periodic verification test at least once every 2 yr [years]
Licensees Proposed Alternative The licensee states that all core spray system (CSS) pumps at QCNPS, Units 1 and 2, have been and will continue to be tested using quarterly and comprehensive test methods in accordance with the ASME OM Code, subsection ISTB, paragraph ISTB-5100, Centrifugal Pumps (Except Vertical Line Shaft Centrifugal Pumps). Pump flow testing of a CSS pump is conducted with pump suction from the torus with water return to the torus. This CSS pump operability and performance testing is currently being performed in accordance with QCNPS, Units 1 and 2, Technical Specification 3.5.1, ECCS [Emergency Core Cooling System] -
Operating.
Licensees Basis for Use The licensee states that data regarding pump flow rates and pressures at various points for each CSS loop are obtained at least every 2 years for comparison with the previously established normal conditions in accordance with the IST program at QCNPS, Units 1 and 2.
Testing and baselining of the pump performance test acceptance criteria are re-performed following major maintenance of the CSS pumps in accordance with ASME OM Code, subsection ISTB, paragraph ISTB-3300, Reference Values. Testing of the CSS pumps at a flow rate of approximately 4500 gallons per minute (gpm) using the existing test return line flow path provides for substantial flow testing in a stable region of the pump curve.
The licensee conducts additional pump performance monitoring for the CSS pumps including pump motor bearing temperature monitoring, vibration monitoring, and periodic sampling of the lube oil. The licensee asserts that performance monitoring of the CSS pumps indicates the pumps will remain capable of meeting their design function with no indication of degradation. If measured parameters are found to be outside the normal operating range or determined to be trending toward an unacceptable degraded state, the licensee states that appropriate actions will be taken. These actions include monitoring additional parameters, review of specific information to identify cause, and potential removal of the pump from service to perform necessary maintenance.
The licensee considers that continued testing in a stable flow range combined with the additional pump performance monitoring provides reliable performance monitoring beyond the requirement prescribed in ASME OM Code, appendix V. This testing is said to reliably validate the ability of each pump to meet the design-basis accident flow rates. The licensee also considers the testing to be effective for detecting mechanical and hydraulic degradation as required by ASME OM Code, subsection ISTB. The licensee requests this alternative pursuant to 10 CFR 50.55a(z)(2) based on its determination that compliance with the PPVT cannot be accomplished without major system modifications. The licensee states that such a significant change to the system represents a hardship or unusual difficulty without a compensating increase in the level of quality and safety. The licensee asserts that the proposed alternative provides reasonable assurance of pump operational readiness and provides an acceptable level of quality and safety.
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Reason for Request===
In accordance with 10 CFR 50.55a, paragraph (z)(2), the licensee proposes an alternative to the pump test requirements of ASME OM Code (2017 Edition), appendix V. With the adoption of the ASME OM Code (2017 Edition) at QCNPS, Units 1 and 2, a new requirement was added to perform periodic verification testing at the pumps highest design-basis accident flow rate. The current system test flow path design is not capable of testing these pumps at these conditions.
The only option for achieving the ASME OM Code test flow rate is to inject into the reactor pressure vessel (RPV) with water from the torus or condensate storage tank. The basis for this request is that compliance with the ASME OM Code requirements would result in a hardship or unusual difficulty with no compensating increase in the level of quality and safety.
The CSS is a low-pressure ECCS designed to inject above the core via a ring header at a flow of 4500 gpm and pressure of 90 pounds per square inch gage (psig). The highest required design-basis accident flow rate for the CSS is 5650 gpm at 0 psig for each CSS pump based on the loss-of-coolant accident fuel analysis. Thus, per ASME OM Code, appendix V, this is the CSS design flow rate that is required for PPVT purposes.
The CSS test return line for each CSS pump is designed to conduct routine system testing at a lesser flow rate of approximately 4500 gpm. This is 80 percent of the highest design-basis accident flow rate. This design allows for testing at a representative point on the pumps performance curve to allow for demonstrating pump performance, but not at the highest design-basis accident flow rate.
To meet the PPVT highest required design-basis accident flow rate without major modification to the testing flow path, the system would have to be lined up to discharge to the RPV at 0 psig.
This flow path has the potential to introduce unwanted contaminants into the RPV and reactor coolant system (RCS), which is contrary to existing NRC, industry, and Constellation guidelines for reactor coolant chemistry controls, thus it has not been used at QCNPS, Units 1 and 2, since 2019. However, when this testing was still performed, the pumps were able to achieve 5650 gpm at 0 psig. The licensee provides information from this testing in Table 1 of its submittal.
The licensee states that compliance to the new PPVT required flow rate using the CSS test line would require an extensive system redesign and modification that would include installation of additional or larger diameter piping and isolation valves, new hydraulic and seismic evaluations, and likely new supports and snubbers. These modifications would also impact multiple safety systems as a portion of the test line is shared with residual heat removal system, high pressure coolant injection system, and reactor core isolation cooling system. This would require extended outage time to install. Such a major modification is costly and burdensome with no compensating increase in the level of quality or safety. Performing these modifications is not warranted because there will be no improvement in the ability to detect pump degradation.
Testing for the PPVT at an alternate flow rate is proposed and would provide a reasonable assurance of pump operational readiness and an acceptable level of quality and safety.
3.2
NRC Staff Evaluation
The ASME OM Code, Mandatory Appendix V, as incorporated by reference in 10 CFR 50.55a, requires safety-related pumps to have a periodic verification test program where the pumps are tested at their highest design-basis accident flow rate and pressure (differential or discharge as applicable). Appendix V requires a PPVT for each pump to be performed at least once every 2 years. To comply with this requirement, the CSS at QCNPS, Units 1 and 2, would have to be updated with an extensive modification. As a result, the licensee asserts that compliance to meet the requirement to test the CSS pumps at the highest design pressure value per Mandatory Appendix V would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Under request RP-01, all CSS pumps will continue to be tested using quarterly and comprehensive test methods in accordance with the ASME OM Code, Subsection ISTB, paragraph ISTB-5100. The highest required design-basis accident flow rate for the CSS is 5650 gpm at 0 psig for each CSS pump. The test return line for each CSS pump is designed for a flow rate of approximately 4500 gpm, which is 80 percent of the design-basis accident flow rate. The NRC staff considers testing at 80 percent of the design-basis accident flow rate at a representative point of the pumps performance curve to support the capability of the CSS pumps to perform their safety functions.
Until 2019, several high-flow tests of the CSS pumps were conducted at QCNPS, Units 1 and 2, which achieved at least 5650 gpm at 0 psig. This information supports the historical capability of the CSS pumps to perform their safety functions at the design-basis accident flow rate. The NRC staff considers this past successful testing of the CSS pumps to support the alternative proposed in request RP-01.
In addition to flow testing, additional pump performance monitoring of the CSS pumps at QCNPS, Units 1 and 2, includes pump motor bearing temperature monitoring, vibration monitoring, and periodic sampling of the lube oil. If measured parameters are found to be outside the normal operating range or determined to be trending toward an unacceptable degraded state, additional actions will be taken such as identification of the cause of the performance degradation and possible removal of the pump from service to perform maintenance. The NRC staff considers these additional performance monitoring activities for the CSS pumps to support the capability of the CSS pumps to perform their safety functions.
To meet the PPVT design-basis accident flow rate, the CSS pumps at QCNPS, Units 1 and 2, would have to be lined up to discharge to the RPV at 0 psig unless major modifications are performed. This flow path has potential to introduce contaminants into the RPV and RCS. The NRC staff considers the potential introduction of containments into the RPV and RCS to support the alternative proposed in request RP-01.
Compliance with the PPVT required flow rate would require an extensive system redesign and modification at QCNPS, Units 1 and 2, which might impact other safety systems. Such a major modification would be expensive and require an extended outage time. In light of the capability to test the CSS pumps at 80 percent of the PPVT design-basis accident flow rate and the additional pump monitoring activities, the NRC staff considers that testing for the PPVT at the alternate flow rate will provide reasonable assurance of operational readiness of the CSS pumps at QCNPS, Units 1 and 2.
Based on its review, the NRC staff has determined that the proposed alternative in request RP-01 is acceptable in accordance with 10 CFR 50.55a(z)(2). The CSS pumps have undergone successful testing at the design-basis accident flow rate in the past, and the proposed alternative includes testing at 80 percent of the design-basis accident flow rate. In addition, request RP-01 includes pump performance monitoring and specified actions if the pump parameters are outside of their normal range or trending toward a degraded state. As a result, the staff finds that the alternative testing proposed in request RP-01 will provide reasonable assurance that the CSS pumps listed in the licensees request will be operationally ready to perform their safety functions. Based on the major modifications at QCNPS, Units 1 and 2, that would be required, the staff finds that compliance to fully meet the appendix V requirements for the CSS pumps would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. Therefore, the NRC staff finds that request RP-01 meets the requirements in 10 CFR 50.55a(z)(2) for the specified CSS pumps at QCNPS, Units 1 and 2.
4.0 CONCLUSION
As set forth above, the NRC staff determined that the proposed alternative in request RP-01 will provide reasonable assurance that the CSS pumps listed in Table 1 of this safety evaluation are operationally ready to perform their safety functions. The NRC staff determined that the licensee has justified that compliance with the testing requirements in the ASME OM Code (2017 Edition) for the pumps listed in Table 1 would result in hardship without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(a)(z)(2).
Therefore, the NRC staff authorizes the proposed alternative in request RP-01 for the sixth IST program interval at QCNPS, Units 1 and 2, which began on August 18, 2023, and is scheduled to end on July 17, 2033.
All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief or an alternative was not specifically requested, and granted or authorized (as appropriate), remain applicable.
Principal Contributor: Thomas G. Scarbrough, NRR Date: September 30, 2024
ML24247A164 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DEX/EICB/BC NRR/DORL/LPL3/BC NAME RKuntz SRohrer SBailey (TScarborough for) JWhited DATE 8/30/2024 9/4/24 8/30/2024 9/30/2024